CAR WILL NOT SHIFT AFTER 45MPH.....
TO EXPLAIN BRIEFLY, MY 1995 PONTIAC GRAND PRIX GTP WILL NOT SHIFT AFTER 45-50MPH IT WILL DROP IN RPMS TO 1500 AND STAY THERE NO MATTER HOW FAR I PUSH THE GAS PETAL.. SOMEONE PLEASE HELP ME HERE IVE HAD SO MANY DIFF ANSWERS FROM ITS MY TRANNY, THEN I WAS TOLD ITS A CLOGGED CATALYTIC CONVERTER.. IVE HAD THIS CHECKED AND THEY SAY NOTHING IS WRONG..
Check all the connectors on your PCM located blow the air filter. The PCM is what determines shift points based on inputs from engine sensors. When working with these connectors have battery disconnected.
PCM is an acronym that stands for Powertrain Control Module. PCM is the onboard computer which is the brain of the engine control system. So basically just disconnect the battery for at least 5 minutes or so..it should reset the computer in your car. Hope that helps :)
It is also possible is is a smililar problem to what the Monte Carlo (same trans in most models) has where the board in the trans fails. If the PCM reset as described above by Aztec and Rachel it is likely to be that board.
its the pcm maybe something unpluged to the tranny but its most likely the problem is the pcm unhook it for 5 to 10 min and you should be good :) good luck
buy a trans am
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